Go for the 6 foot
Ive got a 6ft long x 2ft tall x 18inch wide at the moment and it give you a lot of options Im hoping (unbeknown to my wife) to get a 6x2x2 or maybe even a 7x2x2 when we redo the kitchen this year or next. I got mine from ND aquatics and its been a great tank. But there are some really nice set ups available now with nice stands and overhead lights etc. The maintenance on a 4x2x2 vs a 6x2x2 probably wont be that much different as you will need pipes and pumps to do water changes on the 4x2x2 anyway.
Ive got a 6ft long x 2ft tall x 18inch wide at the moment and it give you a lot of options Im hoping (unbeknown to my wife) to get a 6x2x2 or maybe even a 7x2x2 when we redo the kitchen this year or next. I got mine from ND aquatics and its been a great tank. But there are some really nice set ups available now with nice stands and overhead lights etc. The maintenance on a 4x2x2 vs a 6x2x2 probably wont be that much different as you will need pipes and pumps to do water changes on the 4x2x2 anyway.